The use of macromonomers with pressure-sensitive adhesives (PSA) and for other applications is known. Macromonomers are relatively low molecular weight polymers having a copolymerizable vinyl functional reactive group at one end of the polymer which is capable of copolymerizing with an acrylate group.
U.S. Pat. No. 3,786,116 discloses an anionic polymerization technique used to make macromonomers of styrene, substituted styrenes, butadiene and isoprene. Graft copolymers of poly-alphamethylstyrene and polystyrene with comonomers such as butylacrylate are exemplified. The role of the hard or high glass transition temperature (Tg) macromonomers is to improve the cohesive strength of the network through association of the hard segments. Synthesis of a graft copolymer of polypropylene with a polyisoprene macromonomer by coordination polymerization is also illustrated. The role of the polyisoprene is to modify the impact properties of the hard polypropylene. Use of crosslinkable macromonomers is not taught or suggested.
U.S. Pat. No. 4,551,388 uses a hard poly(vinyl aromatic) macromonomer in an acrylic PSA composition. The role of the macromonomer is to provide cohesive strength to the network through the association of hard domains. U.S. Pat. No. 4,656,213 extends the '388 patent by using tackifiers and optionally a plasticizer for the acrylic phase.
U.S. Pat. No. 4,554,324 deals with a tacky PSA containing a macromonomer having a Tg greater than 20.degree. C. The role of this macromonomer in the PSA is to improve the cohesive strength through the high Tg macromonomer domains. The macromonomers of the '324 patent are non-reactive except for the ability to copolymerize with an acrylate.
U.S. Pat. No. 4,693,935 pertains to combining polysiloxane macromonomers with acrylic comonomers to obtain a PSA with reduced adhesion to surfaces. The adhesives are repositionable adhesives.
U.S. Pat. No. 4,732,808 deals with an acrylic skin adhesive containing a high Tg macromonomer. The role of the macromonomer is to improve cohesive strength.
U.S. Pat. No. 4,833,179 discloses the use of a high Tg macromonomer as a modifier to increase the storage stability of suspension polymer microspheres.
U.S. Pat. No. 4,851,278 discloses acrylic polymers synthesized with high Tg macromonomers which are then used as binders to reduce the transfer of tacky microspheres. The improvement in cohesive strength comes from hard polystyrene domains.
U.S. Pat. No. 5,006,582 discloses the use of hard macromonomers based on polymethyl methacrylate in combination with acrylic monomers and a tackifier for the acrylic phase. The resulting polymer is stated to have high shear properties.
U.S. Pat. No. 5,057,366 disclosed a PSA coated sheet material using the compositions of U.S. Pat. No. 4,454,324.
None of the above patents, all of which are incorporated by reference, contemplate the use of a low Tg acrylic polymer matrix that is formed in the presence of a reactive high Tg macromonomer to improve high temperature properties without adversely affecting the low Tg properties of the acrylic polymer matrix.